The purpose of this project is to increase our understanding of the metabolism of retinoids. Such information must be had before a rational approach can be taken to the design of new retinoids with greater activity in the reversal of preneoplasia in epithelial tissues. The investigation is along two basic lines: 1) The study of the in vitro metabolism of retinoic acid and synthetic retinoids in subcellular systems of target organs, and 2) the study of the absorption, storage, and tissue distribution of synthetic analogs as compared to the natural retinoids.